Distillate oil from still residues



Patented Mar. '1, 1939 1 umrso STATES PATENT orricr.

nrs'rnaa'raon. mom s'rmr. nnsmnais- William H. Carmody, Pittsburgh, Pa., assignor to The Neville Company, a

sylvania No Drawing.

2 Claims.

This invention relates to the recovery of useful products from still residue resultant from the treatment of light oils derived from coal-coking ovens, and particularly to the recovery of a useful solvent oil from such still residue.

During the recovery of aromatic oils from cokeoven gases, it is customary toscrub the gases with a mineral oil in order to extract the aromatic oils contained in the gases; By this scrubbing the mineral oil becomes charged with such solvents as benzol, toluol, xylol, and the crude naphthas. After scrubbing, the aromatic content taken up by the mineral oil is volatilized away from the mineral scrubbing, or wash, oil. The recovered aromatics form coke-oven light oil. After separation of the lighter aromatics of the light oil from the crude solvent naphthas, the lighter aromatics are subjected to purification and to distillation. There remains in the several stills a still residue having its derivation in the coke-oven light oil.

This still residue from coke-oven light oil is a dark viscous material ofa sirupy consistency. Apparently it is a dispersed mixture of resins in -oils, and of a colloidal nature. It possesses in its complete form and natural condition substan tially no utility in the arts.

In order to recovervaluable products from such still residue, I initially subject the still residue flabove 250 C., such as 'a remove a maximumto a distillatio'nand blowing treatment with live steam. In so doing, the still residue is heated samciently to elevate its temperature, to a point at which it is thin and free flowing. Desirably, the temperature is raised to a point substantially temperature within a C. By blowing live steam while maintaining it at the oily content of the may be collected range of 275 C. to 280 through the still residue, such elevated temperature, still residue is carried over,.and

in association with watercondensed from the There remains residually after the oil content of the still residue has been carried over a solid residuum in a quantity approximating 40% the weight 01 the initial still residue. This solid residum is'a hard, black, resin-like material of a When care has been taken to proportion of the initially associated oil, a solid residu having a melting- ,point as high as-.10'7 C. has been obtained. This solid residual material is readily and completely soluble in aromatic solvents such as benzol, -'toluol, and the solvent naphthas. In petroleum benzine, however, it disintegrates rapidly .to give a reddish-amber solution and a flocculent precipitate. Apparently this solid residuum is in brittle nature.

corporation of Penn- Application June 11, 1936. Serial a 85,747

degree alcohol soluble, since a moderate quantity of alcohol may beadded to a benzene solution of the residuum without causing precipitation. Addition of a relatively large proportion of alcohol to a benzene solution of the residuum serves, however, to produce a cloudiness which on standing coagulates into a definite precipitation. This resin-like residuumhas certain distinctive qualities. For example, it shows upon breakage a peculiar grain-like structure not commonly found in pitches or resins. It is capable of taking a high polish, and is usable as a carnauba wax substitute in floor polishes, or the like. It is usable as a sealing agent for the tops of dry cells, and may be used for that and similar electrical purposes. It is compatible with coumarone-indene resins, and may be modified by admixture with those resins for certain purposes, as for the sealingof electrical dry cells, and the like.

The remaining 60% of the initial still residue is then oil distilled and blown oil as above described. This oil, as initially recovered, being thoroughly commingled with water, it is necessary that it be dried before fractionation. The pro-- cedure in separating this residual oil from the water from which it is associated requires distinctive procedure, for the reason that the oilhas aspecific gravity very close to the specific gravity of water and a separation by merely permitting settling of the diverse liquids is not, therefore, efiective. My procedure is'to heat the mixed oil and water to a at normal room temperature.

temperature approaching the boiling point of the i water, such as a temperature of from 90 C. to 95 C., and then permitting the mixture to stand and settle. For some reason, probably that the oil has a higher coeflicient of expansion than water, the' oil and water rapidly stratify at that temperature, and the hot water may be drawn away from beneath the layer of oil.

when removal of water has been approximated by heating and stratificatiomthe last traces of water are removed by raising the temperature of entire body of residual oil the components thereof belong to the same system of hydrocarbons, and the cuts or fractions hereinafter described are therefore primarily arbitrary. It is, however, a

distinguishing feature of this oil that the higher boiling fractions of it retain in large measure the solvent power of the lower boiling fractions. Apparently the oil, taken as a whole, provides in its higher boiling fractions the higher range of hydrocarbon solvents which have not previously been isolated in commercial practice, but which previously have existed merely as produced by synthesis andby a scientific rather than a commercial procedure.

-forerunnings and cyclopentadiene.

The fractions to be described thus represent primary cuts taken within ranges which adapt each fraction particularly to some use, and when distillation range is given are to be considered proximate rather than absolute. ,There is, however, in the major higher boiling cut the quality of higher solvent power with respect to the boiling point and specific gravity of the fraction.

By fractionation oi the residual oil, I have obtained, as preliminary runnings, a cut boiling within the approximate range-of 150 C. to 200 C., which represents approximately 10% of the total volume of recovered and dehydrated oil. This out has a sharp characteristic odor resembling benzol' In certain respects it resembles crude solvent naphtha, being initially pale amber in color, and darkening upon standing. It does not possess, however, any tendency toward polymerization, and in that sense 'is to be considered to be a refined rather than ascomp'aredwith the sharp odor of the preliminary running's. It has a relatively low specific gravity, separating readily from water at normal atmospheric temperature. This cut, which comprises approximately 15% the original volume of the'dehydrated residual oil, is in all-respects, save in its volatility and viscosity, identical with the-higher boiling out immediately herematter to be described. Its higher volatility.

' however, renders the inclusion of any substantial proportion or it in the following out unrow'boiling range .of approximately 275C. to

300 0., and comprises approximately 60% the volume of the total initial dehydrated oil. This fact is so marked that it seems proper to con- 7 sider this cut primarily as the residual oil, considering the lowerboiling and higher boiling fractions, respectively, as preliminary runnings and after-runnings associated with its recovery. This oil is of a light amber color and has a specific gravity of approximately 0.98. It has an aniline point of 26 C., which is closely analogous to the aniline point of refined solvent naphtha and similar aromatic solvents. For purposes of comparison it may be stated that the petroleum solvent kerosene boiling within the same approximate range has an aniline point. approximating 60 C. The solvent power of this relatively high boiling oil'is not greatlyfless than V the solvent power of the preliminary runnings boiling within the range of from 150 C. to 200 C.

The last fraction of the residual oil comes 'over in the boiling range of irom 300 C. to 360 C., and decomposes at the latter temperature. It represents the remaining portion oi the initial dehydrated residual oil. It is very viscous and possesses good solvent power with respect to its boiling range and viscosity. It possesses in many respects the qualities oi a heavy oil consistingof the dimers of coumaroneandindene, and may be used asa plasticizer in certain of the less liquid coating compositions. It is compatible with coumarone-indene resins, withester gums, and with most of the other resins, both synthetic and natural. n I

Returning to the fractionation of residual oil boiling within the approximate range of 275C.

to 300 C., which constitutes approximately 60% the initial volume of the oil,;and which I consider primarily-to be the residual oil, this 011 because it joins within itself the qualities of high solvent power and relatively lovd volatility is peculiarly adaptable to a wide variety of uses.

rli'or example, the fact that this oil is relatively non-evaporative renders it a valuable constituent of printer's inks in whichv previously petroieum derivatives have been unsatisfactorly used or in which there have been used relatively ex pensive synthetically produced oils; As a constituent of printer's ink the high solvent power of the oil is of importance, in that it is capable of retaining in solution resins, drying oils; and dyes which provide other constituents. of the ink.

For other uses advantage may be taken of the unusual Joinder oi, qualitieso! this oil. Whereas benzol, for example, has high solvent power, and evaporates so rapidly from the composition in which it is included that it is to 'be considered solely as an evaporative solvent. This nonevaporative solvent oil is capable of remaining in the composition, such as a coating composition, to iorm wholly or partially a permanent component of the composition. It thushas 'wide applicability to compositions in which slow-dry'-' ing qualities are of importance; and in compositions in which a solvent of substantially nonevaporative' sort is desirable to impart added adhesive qualities to the composition.

This product, namely the oil-distilling within.

the approximate ranzeyof 275 C. to 300 0..

mary" product of the treatment, and the other recoverable products both solid and oily'may be has such strikingly individual and valuable qualities that it is in fact to be considered -'-the pri-' considered as by-products of a treatment for its recovery. ,From the commercialviewpoint; its

sole recovery, other products being discarded, may

aration and purification conducted in light oil recovered. iromcoal-coking ovens for use as a non-,evaporative solvent in printer's ink 'and like compositions, said oil distilling within the approximate range of 275 C. to'300 C.-having a specific gravity of approximately 0.98 and having an aniline point about 26 C.

2. The herein described method of recovering useful products from still residue derived from treatments of separation and purification conducted inlight oil recovered from coal-coking ovens which comprises separating the volatile content of the still residue by blowing live steam through the still residue heated to a temperature substantially above 250 C. adequate to render it thin and free flowing, resultantly to obtain as the volatile content of the still residue 8. distillate aromatic solvent ofl distilling within the approximate range of 150 C. to 360 C. and a hard resin-like residuum as the non-volatile content of the still residue, separating the distillate oil from condensate water by heating the mixed oil and water to a temperature approximating 90 C. and by settling and decantation, purifying the oil so dehydrated, and recovering therefrom the fraction boiling within the approxi- WIULIAM H. CARMODY. 

